The glass transition and relaxation behavior of bulk water and a possiblerelation to confined water

摘要

Due to the widespread importance of water and the difficulty to study it in the so-called no man'sland between 150 and 235 K, deeply supercooled bulk water is currently heavily debated. Itspeculates about its properties from extrapolations of experimental data on bulk water above 235 Kand below 150 K, computer simulations, and experiments on confined water for which the finite sizeeffects may prevent crystallization in the no man's land. However, it is far from obvious howexperimental data on bulk water should be extrapolated to the temperature range of the no man'sland or how relevant results from computer simulations and studies of confined water are for bulkwater. In this paper the structural and dynamical properties of supercooled bulk water are tried to beunderstood from experimental results on confined water and comparisons with bulk water. Wepropose that a similar crossover from a high temperature a-relaxation to a low temperatureβ-relaxation occurs also for bulk water but at a higher temperature than for confined water due tothe larger average number of hydrogen bonds between the water molecules in bulk water. In the caseof bulk water the crossover is expected to occur around the critical temperature T_s≈228 K whenthe buildup of an icelike tetrahedral network structure is completed. The proposed interpretation isthe simplest one that is able to explain many of the peculiar properties of supercooled water